SUBSTITUTION NUCLEOPHILE D'ACETATES DE CYCLENOLS ALLYLIQUES FONCTIONNELS PAR DES ORGANOMETALLIQUES EN PRESENCE DE SELS CUIVREUX. APPLICATION A UNE SYNTHESE RAPIDE DE LA (+/-) MITSUGASHIWALACTONE

Article abstract of DOI:10.1016/S0040-4020(01)81522-2

Substitution of functional allylic cycloalkenol acetates by Grignard reagents (primary, secondary, tertiary-alkyl, vinyl, aryl) in the presence of a catalytic amount (2.5percent equivalent) of cuprous iodide at low temperature, gives high yields of various functional α-substituted cycloalkenes.The reaction can be applied to lithium enolates of esters and need no catalyst, but may be performed with HMPA as cosolvent.It is illustrated by a short (6 steps) and efficient total selective synthesis of (+/-)-mitsugashiwalactone from 2,5-dimethoxytetrahydrofuran with 33percent overall yield.